Flexographic printing plates are adhered to cylindrical print cylinders with a double sided adhesive material, known as "sticky back." This is wrapped around and stuck to the cylinder so that the outer surface of the sticky back is covered by a release sheet. Location holes are bored in the plates, and to ensure that each plate is accurately aligned with each cylinder, pin bars are used to dispose a row of pins along the length of the cylinder, to fit the location holes bored in the plates. Once a pin bar is properly located on a cylinder, and a plate is properly positioned by the pin bar, a portion of the release sheet over the sticky back is cut away, and the matching region of the flexible plate is adhered to the exposed sticky back, to fix the plate in its located position. Then the plate is removed from the pin bar, the pin bar is removed from the cylinder, the release sheet is removed from the rest of the sticky back, and the rest of the plate is adhered to the sticky back around the full circumference of the cylinder.
The pin bars available for mounting flexographic plates this way have been cumbersome and difficult to clamp in an accurately axial position on the cylinder. Their pins have been fixed in axial positions from which they are selectively removable, and these have been inconvenient to accommodate to plates having pin holes in varying locations. Pin bars have also been expensive and have typically fit only a single size cylinder so that they have been required in large numbers, representing a substantial investment. Examples of such prior art pin bars are shown in U.S. Pat. Nos. 4,604,811, and 4,380,956.
I have devised a more convenient pin bar that is easier to use for mounting flexographic printing plates. My pin bar clamps quickly and simply in a position that is accurately parallel with the cylinder axis. Its plate mounting pins are movable axially for speed and convenience in matching the holes drilled in the plates, and once the pins are set in the proper position for a series of plates, they automatically fit all the plates in the series. A single size of my pin bar can fit several sizes of cylinders, and my pin bars are simpler and less expensive than the ones previously available.